Solution for flameproofing cellulosic materials



Patented Oct. 12, 1954 SOLUTION FOR FLAMEPROOFING CELLULOSIC MATERIALS John P. Wadington, Keyport, N. 3., assignor to National Lead Company, New York, N. Y., a corporation of New Jersey No Drawing. Application February 21, 1952, Serial No. 272,893

Claims.

This invention relates to the treatment of cellulosic material. More specifically it relates to the treatment of fibrous celluosic material to render the same fire-resistant, and to solutions used in such treatment.

Considerable interest has been aroused in the textile and related industries by the recent introduction of fire-retarding agents based on soluble titanium compounds. Among the most effective of such agents are solutions of titanium chloride acylates. Such solutions are clearly described and claimed in co-pending application Serial No. 229,272,'filed May 31, 1951, now Patent No. 2,658,000.

In using flame-retarding solutions of the type mentioned above, it has ordinarily been found desirable to operate with relatively high concentrations of titanium in the solution, for example, from 40 to 150 grams per liter titanium. Dilution of the solutions to titanium concentrations substantially below 40 grams per liter was found to have detrimental effects upon the stability of the solutions, causing the titanium values to hydrolyze as a white precipitate. Such behavior in the solution adversely afiects the appearance, texture, and fire retardancy of the finished material and in some cases makes the solution completely unusable.

An object of this invention, therefore, is to provide a treating agent suitable for rendering cellulosic materials fire-resistant. Another object is to produce a fire-retarding agent which can be prepared and maintained at relatively low concentrations of titanium without destroying its useful stability. Another object is to produce a dilute titanium chloride acylate solution which may be used to treat light weight materials without impregnating the material with unnecessarily high amounts of agents.

These and other objects will become apparent from the following more complete description of the instant invention.

In its broadest aspects, this invention contemplates a dilute solution adapted for imparting fire-resistance to cellulosic materials, comprising an aqueous solution of hydrochloric acid and a titanium chloride acylate, said acylate being selected from the group consisting of formate, acetate and propionate, the chloride values of said titanium chloride acylate and said hydrochloric acid being present in amount aggregating from 90 to 200 grams per liter Cl.

This invention further contemplates such a solution which also contains antimony trichloride.

The concentration of titanium chloride acylate may be varied over a wide range, but for the particular purposes of this invention, it is preferred to maintain a titanium concentration between about 15 and about grams per liter Ti in the solution.

The concentration of hydrochloric acid in the solutions of this invention may also be varied over a wide range. In general, it is preferred to have the acid concentration such that the total chlorides present as titanium chloride acylate and hydrochloric acid be present in amount from about 90 to about 200 grams per liter Cl. Solutions containing 90 grams per liter of Cl are in all cases stable over at least moderate periods of time permitting batch-wise manufacture and reasonable storage time. Increasing amounts of chlorides, however, further stabilize the solution, and solutions containing more than about 120 grams per liter Cl may be stored for extended periods of time. Solutions containing excessive concentrations of soluble chlorides, however, tend to be acidic in character, and exert a tenderizing efiect on the materials treated. It is, therefore, preferred to maintain a chloride concentration in the solution no higher than about 200 grams per liter C1.

The acylate ion should be a low-molecularweight group, such as formate, acetate, or propionate, preferably the acetate, and should be present in amount to give at least one and preferably not over three moles of acylate for each mole of titanium present in the solution.

The presence of antimony compounds such as SbCls enhances the fiameproofing properties of I the solutions of this invention, and also contributes to increased resistance to afterglow. While even small amounts of antimony may be used with beneficial effect, it is preferred to have present at least 1.7 parts of Sb for each part of Ti in the solution. Amounts of antimony higher than about 3.4 parts Sb for each part of Ti are to be avoided, however, since higher concentrations of antimony appear to exert a nucleating effect and adversely afiect the stability of the solutions. When antimony is present in the solutions of this invention, it will normally be present as SbC'l3, and the chloride values of the SbCls are in addition to the previously-mentioned chloride values of the titanium chloride acylate and free hydrochloric acid.

The flameproofing solutions of this invention are particularly adapted forfiameproofing lightweight cellulcsic materials. When the relatively concentrated solutions of the above-mentioned co-pending application were used, the use of these relatively concentrated solutions resulted in the pickup and retention on the cloth of more of the titanium values than was preferred for optimum flameproofing. When using the dilute solutions of the present invention, however, the degree of pickup and add-on may be more readily controlled and no more of the titanium values need be applied to the cloth than is required for flameproofing.

In addition to offering a means for controlling the amount of titanium picked up, however, the solutions of the present invention offer a further advantage in that the titanium values which are picked up are apparently more efiiciently utilized. The reason for this more efilcient utilization is not definitely known but it may be associated with the lower viscosity and increased penetrating power of the more dilute solutions with respect to the cellulosic fibers. At any rate, it has been found that even when fiameproofing the heavier fabrics, such as duck, denim and the like, the amount of titanium add-on required for efilcient flameproofing is smaller when using the solutions of the present invention than when using the relatively concentrated solutions of the above-mentioned co-pending application.

Fibrous cellulosic materials which may be rendered fire resistant by the process of the instant invention include fabrics such as cotton, linen, regenerated cellulose, viscose and cellulose acetate, also natural fibers such as kapok, hemp, wood and wood products, such as pressed board, cardboard, batting, paper, wood flour, saw dust and the like. The cellulosio material is treated with the titanium salt solution by any convenient means such as by dipping the material in the solution or by spraying the solution on the material. Any excess solution on the cellulosic material may be removed, for example, by squeezing between rolls, deliquoring in a filter press or any other appropriate method depending on the physical nature of the material. It is preferred to leave a quantity of solution on the material about equal to the weight of the material itself, i. e. a weight pickup of about 100%. The titanium salt solution impregnated in the cellulosic material is gelatinized, preferably by exposing the treated material to the atmosphere for a short interval of time. Satisfactory results have been obtained when the exposure is such as to reduce the weight of solution held by the cellulosic material to about /2 to about A,, of its original weight. The cellulosic material containing the gelatinized treating agent is then subjected to an alkalizing agent in order to raise the pH of the treated material to above 7.5, preferably above 9.0, but not exceeding 12.0, and finally washed and dried.

It has been found that the preferred amount of impregnant on the final material (dry basis) is about 5 to 8% of the weight of the fibrous cellulosic material when the dilute titanium chloride acylate solution is used alone, while about 8 to 14% is preferred when the combination of titanium chloride acylate and antimony chloride is employed. The entire process may be carried out at room temperature although, if desired, temperatures up to 60 C. may be employed.

The exact nature of the physical and chemical changes that take place during this process is not completely understood. However, the solution of titanium chloride acylate is apparently converted to a transparent gel which adheres tenaciously to the cellulosic material and is not removed by subsequent washing. It may be held in the pores or between the fibers of the cellulosic material, may be absored or adsorbed on the surface or may react to some extent with the cellulosic material itself.

To illustrate preferred embodiments of this invention, the following examples are presented:

EXAMPLE I 794 parts of water and 74 parts of concentrated 36% HCl were mixed in a glass-lined vessel. To this mixture was added 282 parts of titanium dichloride diacetate powder which had been previously prepared by a vapor phase reaction between titanium tetrachloride and glacial acetic acid. Artificial cooling was supplied to keep the temperature of the mixture below 40 C. during the mixing period. The solution was analyzed and was found to contain 54 grams per liter titanium, 102 grams per liter Cl (including the chloride values of both the free HCl and the titanium chloride acetate) and grams per liter acetate.

This solution was used for treating a cotton poplin cloth weighing 4.5 ounces per square yard.

The cloth was immersed in the solution for 2 minutes and was passed through a hand wringer. The operation was repeated (immersed and wrung again) to obtain good soaking. The treated cloth was then partially dried by exposing the cloth to the atmosphere for 2 hours to gelatinize the treating agent on the cloth. The gelatinized treated cloth was then immersed for 5 minutes in a solution of sodium hydroxide containing 200 grams per liter NaOH to alkalize the solution retained on the cloth. The pH of the retained solution held by the cloth was 9.5. The excess solution was squeezed out of the cloth by passing the cloth through a hand wringer. The cloth was then washed well with water until the retained solution had a pH of 8.0 and the washed cloth was then thoroughly dried. The entire procedure was carried out at room temperature. The treated cloth was subjected to the standard flame test and the results are recorded in Table I.

The standard flame test is called the 45 degree microburner test and consists of exposing the smooth side of the fabric at an angle of 45 degrees, inch above the top of a burner. The flame, 1% inches in length, is played onto the fabric for 12 seconds. Afterflaming and afterglow data are recorded in seconds. The procedure and apparatus assembly has been developed by the Quartermaster Corps of the United States Army and is described by Major Robert W. Little, Quartermaster Corps in his book entitled Flameproofing Textile Fabrics, pages 117 to 119 (Rheinhold Publishing Corporation, 1947).

A second portion of the treated cloth was laundered in a tumbling chamber with 0.5% neutral soap solution at 70 C. for 45 minutes. The laundered cloth was then rinsed with water, dried and again tested for flameproofing. Results of both tests are recorded in Table I.

EXANLPLE II 734 parts of water, 112 parts of concentrated 36% HCl and 237 parts of titanium dichloride diacetate were used to prepare a solution according to the procedure described in Example I. To the resulting solution were added parts of SbClz. The finished solution containing the antimony was analyzed and was found to contain 45 grams per liter titanium, 173 grams per liter C1, 124 grams per liter acetate and 80 grams per liter antimony. This quantity of antimony corresponds to 70 grams per liter Cl, leaving 103 grams per liter C1 present as free hydrochloric acid or in combination with the titanium. This solution was allowed to stand several-days in order to test its stability. No change in appearance or composition could be detected. .The solution was then used to fiameproof a 4.5-ounce poplin type of cotton cloth, accordingto the procedure described in Example I. The fire resistance properties of the cloth were tested by the 45 degree microburner test both before and after laundering. Results are given in Table I.

EXAMPLE III A fiameproofing solution Wasprepared according to the method described in co-pending application, Serial No. 229,272, by slowly adding an aqueous solution of lead acetate to an aqueous solution of titanium tetrachloride while maintaining the temperature below 25- C. and filtering to remove the lead chloride from the titanium chloride acetate solution. 1

The resulting titanium chloride acetate solution was analyzed and was foundto contain 155 grams per liter Ti, 528 grams per liter Cl, 365 grams per liter acetate and 282 grams per liter antimony. To 835 parts of this solution were added 463 parts of 36% HCl, and subsequently 1470 parts of Water. The resulting solution was analyzed and was found to contain 30 grams per liter Ti, 167 grams per liter Cl, 71 grams per liter acetate, 55 grams per liter antimony. Since the C1 requirements of this concentration of antimony is 48 grams per liter, there remain 119 grams per liter of Cl present either as free hydrochloric acid or in combination with th titanium. This solution was used to flameproof a 9-ounce herringbone twill cotton cloth according to the same procedure used in Example I and the treated cloth was tested for flameproofing properties. The results of the test are given in Table I.

EXAMPLE IV Another flameproofing solution was prepared according to the method of Example III. The resulting solution was analyzed and found to contain 115 grams per liter Ti, 269 grams per liter acetate and 169 grams per liter Cl (including the Cl values of the free HCl and of the titanium chloride acetate). To 250 parts of this solution were added 456 parts of dilute hydrochloric acid having a concentration of 80 grams per liter HCl. The diluted solution was analyzed and found to contain 35 grams per liter Ti, 82 grams per liter acetate, and 107 grams per liter Cl (again including the Cl values of the free RC1 and of the titanium chloride acetate). The diluted solution was tested for flameproofing properties by fiameproofing a piece of 3-ounce organdy cotton cloth. The results are recorded in Table I.

EXAMPLE V 1000 parts of aqueous titanium tetrachloride solution containing 500 parts of titanium tetrachloride were mixed in a glass-lined vessel with 1505 parts of basic lead carbonate,

Pb: (OI-I) 2(CO3) 2 The temperature of the solution was maintained below 40 C. during the mixing operation and the solution was subsequently cooled to 20 C. to insure substantially complete precipitation of the lead chloride product. The solution was filtered to remove the lead chloride and diluted with 875 parts of water, and 398 parts of propionic acid 6 were added to the diluted solution. The resultant product was analyzed and was found to be substantially pure titanium dichloride dipropionate in aqueous solution having a concentration of 66 grams per liter Ti. To 1485 parts of this solution were added 175 parts of aqueous 36% HCl and 610 parts of water in the order named. The resultant solution was ana lyzed and was found to contain 49 grams per liter Ti, 105 grams per liter Cl, and 151 grams per liter propionate. The diluted solution was used to fiameproof a piece of 5.5-ounce oxford cotton cloth and tested according to the methods previously described. Results are recorded in Table I. l

EXAMPLE VI 1475 parts of aqueous titanium tetrachloride containin 191 parts of Ti, 3320 parts of basic lead carbonate, and 550 parts of 88% formic acid were processed according to the procedure described in Example V to produce a solution of titanium monochlorid triformate having a concentration of 131 grams per liter Ti. To this solution were added 784 parts of aqueous 36% HCl, and subsequently 2530 parts of water. The resulting solution was analyzed and found to contain 41 grams per liter Ti, 118 grams per liter formate, and 92 grams per liter Cl; A piece of 5.5-ounce oxford cotton cloth was flameproofed with this solution and tested according to the procedure previously described. Results are in Table I. 1

EXAMPLE VII The solutions prepared as described in Examples I, HI, IV, V, and VI were each examined and again tested for flameproofing properties after ordinary shelf storage for a. period of one week after their preparation. All were found to be substantially unchanged in appearance, composition and flameproofing properties.

A fibrous cellulosic material treated with a solution of titanium chloride acylate retains a useful measure of flame-resistant properties upon laundering. However, when the cellulosic material is treated with a combination of agents, that of a solution of titanium chloride acylate and antimony chloride, the flame and glowresistant characteristics are maintained after repeated laundering. able effects on flame and glow-resistance, the antimony chloride appears to have a beneficial effect upon the resistance of the titanium com pounds to removal by laundering.

Recoveries of both titanium and antimony values are substantially during processing. The amounts of titanium and antimony orig inally absorbed on the fibrous cellulosic material are equal to the amount retained in the final material after processing.

When the titanium-based fiameproofing solutions described prior to the present invention are used in excessively diluted form, the titanium In addition to its favorvalues tend to be present in substantially opaque form, the treated material has an unpleasant chalky tone and a white dust may be continually removed from the surface. -When the comparatively dilute fiameproofing solution of this invention is employed, however, the titanium values are fixed in the material in a form which does not substantially-alter the appearance-or texture of the material. Thetreatment process is simple, convenient and economical'to use. By employment of this invention, fibrous cellulosic materials may be treated to render them permanently resistant to fire, with equal efiectiveness and smaller titanium consumption when compared with previous titanium-based fiameproofing agents.

While this invention has been described and illustrated bythe examples shown, it is not intended to be strictly limited thereto and other modifications and variations may be employed within the scope of the. following claims.

I claim:

- 1. A dilute solution adapted. for imparting fire resistance to light weight cellulosic materials, comprising an aqueous solution of hydrochloric acid and a titanium chloride acylate, said acylate being selected from the group consisting of formate, acetate and propionate, said titanium being present in amount from 15 to 40 grams per 8. liter, said acylate being present in amount from 1.0 to 4.6 grams for each gram of titanium said acylate amounting to not less than 15 nor more than 184 grams per liter, the chloride values of said titanium chloride acylate and said hydrochloric acid being present in amount aggregating from 90 to 200 grams of Cl per liter.

2. A solution according to claim 1 which further comprises antimony trichloride, said antimony trichloride being present in amount to give from 1.7 to 3.4 grams Sb for each gram of titanium said antimonyv amounting to not less than 25.5 nor more than 136 grams per liter Sb, the chloride values of said antimony trichloride being in addition to said 90 to 200 grams of 01 per liter.

3. A solution according to claim 1 in which said acylate is acetate.

4. A solution according to claim 1 in which said acylate is formate.

5. A solution according to claim 1 in which said acylate is propionate.

Name Date Number Lane et a1 Oct. 9, 1952 

1. A DILUTE SOLUTION ADAPTED FOR IMPARTING FIRE RESISTANCE TO LIGHT WEIGHT CELLULOSIC MATEIALS, COMPRISING AN AQUEOUS SOLUTION OF HYDROCHLORIC ACID AND A TITANIUM CHLORIDE ACRYLATE, SAID ACYLATE BEING SELECTED FROM THE GROUP CONSISITNG OF FORMATE, ACETATE AND PROPIONATE, SAID TITANIUM BEING PRESENT IN AMOUNT FROM 15 TO 40 GRAMS PER LITER, SAID ACYLATE BEING PRESENT IN AMOUNT FROM 1.0 TO 4.6 GRAMS FOR EACH GRAM OF TITANIUM SAID ACYLATE AMOUNTING TO NOT LESS THAN 15 NOR MORE THAN 184 GRAMS PER LITER, THE CHLORIDE VALUES OF SAID TITANIUM CHLORIDE ACYLATE AND SAID HYROCHLORIC ACID BEING PRESENT IN AMOUNT AGGREGATING FROM 90 TO 200 GRAMS OF C1 PER LITER. 